Biomedical Engineering Reference
In-Depth Information
A
ISI −
t
−48
ref
−50
−52
−54
−56
−58
−60
−62
B
0
50
100
150
200
250
300
350
400
0.8
0.6
0.4
0.2
0
0
50
100
150
200
250
300
350
400
C
−48
−50
−52
−54
−56
−58
−60
−62
0
50
100
150
200
250
300
350
400
Time (ms)
Figure 15.1
Leaky integrate-and-fire neuron model in response to stochastic inputs.
(A)
.Sample
paths of the membrane potential
V
(
)
(
)
t
in response to a stochastic current
I
t
obeying
Equation (15.3) with Poisson spike trains, with
J
E
J
I
=
=
.
=
=
0
2mV,
C
E
C
I
1000,
n
E
=
9Hz,n
I
=
0
.
5 Hz. The resulting steady-state voltage is
V
ss
=
−
53 mV (thin
s
V
/
solid line) with a standard deviation of
38 mV (thin dotted line). Three
sample paths (different colors) are shown from the moment when the neuron starts to
integrate its inputs (t
re f
=
2
=
1
.
reaches threshold
for the first time. The time it takes for this to happen is called the first passage time
and the total time in between two consecutive spikes is the inter-spike interval (ISI).
Threshold (
V
th
=
−
2 ms after the previous spike) until
V
(
t
)
50 mV) is shown as a thick dashed line (Continued).
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